CONFIG_GDBSTUB_IMMEDIATE is not available for thedefaultarchitecture x86.
Result is shown for architecture mn10300
default or selected kernelversion does not have config value CONFIG_GDBSTUB_IMMEDIATE.
Result is shown for kernelversion 6.7-rc3

Break into GDB stub immediately

configname: CONFIG_GDBSTUB_IMMEDIATE

Linux Kernel Configuration
└─>Kernel hacking
└─>Break into GDB stub immediately
In linux kernel since version 2.6.12  
If you say Y here, GDB stub will break into the program as soon as
possible, leaving the program counter at the beginning of
start_kernel() in init/main.c.

depends
CONFIG_GDBSTUB